Information on chromosomes is essential for the progress of genetic and biotechnological studies. In this paper, recent progress on studies of chromosome observation in deciduous fruit trees is reviewed. (1) An enzymatic maceration method, preparing good chromosome samples from plants with small chromosomes, was developed for Prunus, Pyrus, Malus, and Diospyros. (2) Some morphologically similar chromosomes could be distinguished by means of the banding technique using fluorochrome staining in Prunus and Pyrus. In addition, the divergence of chromosome configuration seems to be very low or non-existent in view of fluorescent banding patterns in both genera. (3) The number and location of 5S and 18S-5.8S-25S rDNA sites were detected by fluorescent in situ hybridization (FISH) in Prunus, Pyrus, Malus, and Diospyros. The sites of retrotransposons were also visualized by FISH in Pyrus. These results provided fundamental information on the chromosomes. Chromosomal location of the S (self-incompatibility) locus in Malus was also revealed by FISH. In Diospyros, the results of FISH as well as genomic in situ hybridization (GISH) offered new findings on the phylogenetic relationships in this genus and chromosome composition of somatic hybrids.

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Two anatomical features of cells derived from the pericycle of the roots of Feijoa sellowiana are reported: (1) appearance of endodermis-like cell layer with a Casparian strip, which was confirmed by histological examination; (2) occurrence of a thick wall cell between endodermis-like cells. These features were considered to develop as follows: two tangential cell walls appeared successively in the pericycle cells, resulting in the formation of three cell layers. The walls of the cells of the outer layer, adjacent to the endodermis, became thicker on the interior side of the cell and heavily encrusted with lignin. The walls of the cells in the middle layer derived from the pericycle became suberized and developed into Casparian strips. These cells subsequently developed into endodermis-like cells. The innermost cell layer derived from the pericycle retained their original morphology for a while, but again divided tangentially and developed as mentioned above. Consequently, in aged roots, there were several layers, in which endodermis-like cells with Casparian strips alternated with cells with thick inner walls. The tangential width of endodermis-like cells reduced in sequence from the outer to inner layer. It is quite important to know how the anatomical features of feijoa trees appear under different soil conditions.

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A questionnaire survey was conducted in Yamanashi Prefecture in the course of adapting a wearable robotic suit, which was originally developed for assisting human care (Yonetake and Toyama, 2005), to agriculture. Among various farm operations, farmers had a heavy workload when grape berry thinning followed by cluster shaping and pruning, and 58% of farmers hoped to buy a wearable agri-robot suit that may support their arms, legs, and back. Using the main Ovako Working Posture Analysis System (OWAS), physical workload was evaluated during pruning and berry thinning in vineyards on a slope and flatland; pruning was a heavier workload than berry thinning irrespective of the farm topography and, for both operations, working on the slope was a heavier workload. According to the second OWAS working posture percentages for the relative proportions of the postures of different body parts, workers have to maintain a static posture by raising the arms at or above shoulder level for more than 70% of the total working time in berry thinning. The arm posture in berry thinning was classified as AC3 and corrective measures are necessary as soon as possible. In the OWAS analysis system, although pruning was evaluated to have a higher level of physical stress than berry thinning, farmers felt that it is a lighter workload because it involves various postures, such as walking and sitting, whereas in berry thinning the farmer has to maintain the same posture by raising the arms and farmers especially felt arm fatigue while berry thinning. These results suggested that a mechanical support system is necessary to reduce the workload of grape farmers. Thus, in Japanese grape production, a wearable agri-robot suit focused on a support system for the back, arms and legs with free and rapid movement of the wearer might be an alternative solution to reduce the workload of grape farmers.

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One of the main factors for the lower rating of Japanese pear (Pyrus pyrifolia, cv. Kosui) is contamination of core-rotten fruit in the market. An acoustic resonance method originally developed to measure firmness of fruit with the second resonant frequency was applied to the detection of core rot fruit. Second and third resonant frequencies of ‘Kosui’ Japanese pear with different degrees of core rot were nondestructively measured by a resonant method. Resonant frequency of fruit was determined by sandwiching fruit between the vibrator and detector of a resonant device. Obtained vibration voltage signals were analyzed by fast Fourier transformation. An infected pear with core rot was artificially prepared with injections of conidia suspension of Phomopsis sp. or Colletotricum sp. into the fruit on the tree. Degree of core rot was estimated by the area of the equatorial plane of cut surface. Fruit with less than 500 Hz second resonant frequency had core rot of more than 5% of fruit volume. Discrimination rate was 96.9%. Second resonant frequency more effectively discriminates infected pears with more than 5% core rot from that with less than 5% than the third resonant frequency.

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The changes in the volume of carbohydrates assimilated each month from summer (Aug.; 2 months after harvest) to late fall (Nov.; just before defoliation) in each organ of the Japanese apricot (Prunus mume Siebold & Zucc.) ‘Nanko’ tree were determined until May the following season. The ¹³C concentrations in the young fruits and new leaves were significantly low at the beginning of May. This phenomenon indicates that their growth depends on current instead of reserve carbohydrates. In May, carbohydrates assimilated in Aug., Sep., and Oct. were mainly transported to 2-year-old twigs (current twigs at ¹³C feeding time), roots, and trunk, respectively. Carbohydrates assimilated in Nov. were mainly transported to the flower buds with subsequent flowering at a significantly greater level, and barely transported to the perennial organs. These findings show that carbohydrates that are assimilated each month contribute to different organs and, particularly, that those assimilated in Nov. are important for the growth of flower buds and subsequent flowers; therefore, healthy leaves should be maintained until defoliation for stable production of the fruit of the Japanese apricot tree.

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The objective of this study was to clarify the factors that influence saponin biosynthesis, with an emphasis on protodioscin, a major saponin compound in white asparagus spears. We investigated the effects of methyl jasmonate (MeJM) treatment on protodioscin content in white spears harvested by spring semi-forced and winter-forced cultivation. Protodioscin content was determined using high performance liquid chromatography equipped with an evaporative light scattering detector. Protodioscin was mainly localized in the lower region of the spears. In the spring semi-forced cultivation system using the film-cover method, the protodioscin content in white spears harvested from the MeJM plot was significantly higher than in those harvested from the control plot throughout the sampling period. MeJM also significantly enhanced protodioscin biosynthesis in a dose-dependent manner in the experiment conducted under winter-forced cultivation. These results suggest that saponin biosynthesis in white spears is associated with plant defensive reactions triggered by jasmonate. In addition, bitterness in film-covered white spears could be artificially controlled in commercial fields by MeJM treatment.

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In this paper, we describe a new artificial flower-inducing treatment, intermittent low temperature storage, which we suggest could be a low-cost and useful technology for the forcing of June-bearing strawberries. Tray-grown ‘Nyoho’ plants were placed in a refrigerator (13°C, in the dark) for 4 days and then transferred to an outdoor shelter with 50% shading, also for 4 days (4D/4D). Plants were transferred at noon and this 4D/4D cycle was repeated twice. Similarly, 3D/3D and 2D/2D cycles were applied 3 and 4 times, respectively. The outdoor conditions during the period of treatment from late August to mid-September were as follows: mean daily temperature, 22.5 to 29°C; and day length (sunrise to sunset) 12.2 to 13.1 h. The efficient use of a refrigerator could be achieved by alternately subjecting two groups of plants to the same duration of low temperature in the dark and outdoor conditions. Treated plants were grown on peat bags and flowering performance was compared with untreated controls and continuously cold-stored (12D) plants. In intermittently cold-stored plants, flowering was significantly earlier than that in untreated controls by 6 to 10 days. Compared to the continuous 12D plants, flowering was 15 and 4 days earlier in 4D/4D plants within the plots planted on September 13 and 17, respectively. The 2 to 4 days under outdoor conditions imposed in the low temperature storage apparently induced uniform flower initiation through the improvement of carbohydrate nutrition in strawberries. Although further studies are required to establish the most effective treatment procedures, intermittent low temperature storage could be a useful new flower-inducing technology for early forcing of June-bearing strawberries.

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Vase life of cut lily flowers is limited by fading of petal color before abscission. As petal color changes continuously, it is difficult to determine when vase life ends. We investigated the relationship between declines in ornamental value (visible flower senescence) as judged by human subjects and petal color throughout vase life using cut flowers of the yellow lily. We also examined petal dry weight and thickness to clarify the temporal relationship between visible flower senescence and physiological petal senescence. Our results showed that visible flower senescence was sensitive to changes in petal saturation, which was reflected by the chroma value. The chroma value started to decrease in association with a decline in total carotenoids from day 4 after anther dehiscence. Visible flower senescence was marked on the sixth day when the lilies lost their ornamental value rapidly and their vase life came to an end. On the other hand, signs of physiological petal senescence were evident from the first day when petal dry weight and thickness started to decrease gradually. The progress of physiological petal senescence was reflected in the change in hue angle, which represents the color phase. Our results suggest that changes in the chroma value of yellow lily petals reflect visible flower senescence, which affects vase life. The onset of visible flower senescence is delayed by 3 days relative to physiological petal senescence due to maintenance of adequate carotenoid contents in petals during the early stage of flowering.

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We cloned seven cDNAs coding for ubiquitin (polyubiquitin) (DcUbq1–7) from carnation petals: DcUbq1, 2, 3 encoded polyubiquitins consisting of five ubiquitin monomers; DcUbq4, three monomers and DcUbq5, 6, 7, a monomer. The 3'-UTR nucleotide sequences were separated into three groups; two were specific to DcUbq1 and DcUbq2, respectively, and the third was almost always common to other genes (DcUbq3–7). The transcript levels of DcUbq1 and DcUbq2 in petals fluctuated during flower opening, whereas those of DcUbq3–7 remained unchanged except for an increase in the last stage. On the other hand, during flower senescence, the transcript levels of DcUbq1 and DcUbq2 increased at later stages, and those of DcUbq3–7 remained almost constant during the process. Based on these findings, we suggest an association of ubiquitin gene expression with petal growth during flower opening and petal wilting during the senescence of carnation flowers through the degradation of specific proteins by the ubiquitin-proteasome system. Furthermore, we showed the successful use of DcUbq3–7 transcripts as a normalizing standard in the determination of transcript levels of a target gene in senescing carnation petals, where massive degradation of RNA, such as actin mRNA and rRNA, usually occurs, causing inaccuracy in the estimation of transcript levels of interest.

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Lilium brownii (F. E. Brown) Miellez var. colchesteri E. H. Wilson has a unique characteristic in its flower color, which changes from yellowish-cream to white one day after anthesis. To elucidate the mechanism of flower color change in this species, the content and composition of carotenoids were analyzed during two days of anthesis. The major carotenoids that contributed to the yellowish-cream color of the tepals were lutein, zeaxanthin, and β-carotene. Analysis showed an obvious decrease in total carotenoid content of the tepal, indicating that the flower color change is caused by the reduction of the total carotenoid content after anthesis. To reveal the factor that controls carotenoid content in the tepals, we isolated carotenoid cleavage dioxygenase 4 (LbCCD4) gene and analyzed the number of LbCCD4 messages by quantitative real-time PCR. The transcription level of LbCCD4 gene increased and reached the maximum level 12 hours after anthesis. The results suggest that the carotenoids in yellow tepals of L. brownii var. colchesteri degraded into colorless compounds by carotenoid cleavage dioxygenase and subsequently resulted in white flowers.

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